1. Technical Field
The invention is related to dynamic friction measurement and, more particularly, to an apparatus and a method for measuring the dynamic coefficient of friction between two objects with relatively sliding surfaces.
2. Discussion of Related Art
The coefficient of friction is the ratio of the friction force to the normal force. Previous devices and methods determine the frictional force by an average of measurements, such as the mean of peak-to-peak values, over a period of time. Further, prior devices and methods typically use a weight to provide the normal force. The weight, however, has mass, and thus inertia. During dynamic sliding of two objects for these prior devices and methods, inertial forces develop from accelerations of the mass. As a result, the measured frictional force is in error by the amount of the inertial force, which is equal to the mass multiplied by acceleration of the mass.
In accordance with the teachings of the present invention, a device and a method that measures the dynamic coefficient of friction and correctly adjusts the calculation for errors caused by the inertial force is disclosed. A first object having a sliding surface movably touches a second object. An accelerometer and load cell is adjustably mounted to the first object with its longitudinal axis of sensitivity aligned parallel to a direction of motion of said first object. A computational device determines a frictional force correct for inertial forces from measured electrical signals produced by said load cell and said accelerometer.